feat(integration): 完善外部 API 對接邏輯與安全性

1. 新增 API Rate Limiting (每分鐘 60 次)
2. 實作 ProductServiceInterface 與 findOrCreateWarehouseByName 解決跨模組耦合問題
3. 強化 OrderSync API 驗證 (price 欄位限制最小 0、payment_method 加上允許白名單)
4. 實作 OrderSync API 冪等性處理，重複訂單直接回傳現有資訊
5. 修正 ProductSync API 同步邏輯，每次同步皆會更新產品分類與單位
6. 完善 integration API 對接手冊內容與 UI 排版

app/Modules/Inventory/Contracts/InventoryServiceInterface.php

@@ -131,4 +131,12 @@ interface InventoryServiceInterface
      * @return array
      */
     public function getDashboardStats(): array;
+
+    /**
+     * 依倉庫名稱查找或建立倉庫（供外部整合用）。
+     *
+     * @param string $warehouseName
+     * @return object
+     */
+    public function findOrCreateWarehouseByName(string $warehouseName);
 }

app/Modules/Inventory/Contracts/ProductServiceInterface.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Modules\Inventory\Contracts;
+
+/**
+ * 產品服務介面 — 供跨模組使用（如 Integration 模組）。
+ */
+interface ProductServiceInterface
+{
+    /**
+     * 透過外部 POS ID 進行產品新增或更新（Upsert）。
+     *
+     * @param array $data
+     * @return object
+     */
+    public function upsertFromPos(array $data);
+
+    /**
+     * 透過外部 POS ID 查找產品。
+     *
+     * @param string $externalPosId
+     * @return object|null
+     */
+    public function findByExternalPosId(string $externalPosId);
+}

app/Modules/Inventory/InventoryServiceProvider.php

@@ -4,13 +4,16 @@ namespace App\Modules\Inventory;
 
 use Illuminate\Support\ServiceProvider;
 use App\Modules\Inventory\Contracts\InventoryServiceInterface;
+use App\Modules\Inventory\Contracts\ProductServiceInterface;
 use App\Modules\Inventory\Services\InventoryService;
+use App\Modules\Inventory\Services\ProductService;
 
 class InventoryServiceProvider extends ServiceProvider
 {
     public function register(): void
     {
         $this->app->bind(InventoryServiceInterface::class, InventoryService::class);
+        $this->app->bind(ProductServiceInterface::class, ProductService::class);
     }
 
     public function boot(): void

app/Modules/Inventory/Services/InventoryService.php

@@ -590,5 +590,22 @@ class InventoryService implements InventoryServiceInterface
             'abnormalItems' => $abnormalItems,
         ];
     }
-}
 
+    /**
+     * 依倉庫名稱查找或建立倉庫（供外部整合用）。
+     *
+     * @param string $warehouseName
+     * @return Warehouse
+     */
+    public function findOrCreateWarehouseByName(string $warehouseName)
+    {
+        return Warehouse::firstOrCreate(
+            ['name' => $warehouseName],
+            [
+                'code' => 'SALES-' . strtoupper(bin2hex(random_bytes(4))),
+                'type' => 'system_sales',
+                'is_active' => true,
+            ]
+        );
+    }
+}

app/Modules/Inventory/Services/ProductService.php

@@ -2,13 +2,14 @@
 
 namespace App\Modules\Inventory\Services;
 
+use App\Modules\Inventory\Contracts\ProductServiceInterface;
 use App\Modules\Inventory\Models\Product;
 use App\Modules\Inventory\Models\Category;
 use App\Modules\Inventory\Models\Unit;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Log;
 
-class ProductService
+class ProductService implements ProductServiceInterface
 {
     /**
      * Upsert product from external POS source.
@@ -45,8 +46,8 @@ class ProductService
                 $product->code = $data['code'] ?? $product->external_pos_id;
             }
             
-            // Handle Category (Default: 未分類)
-            if (empty($product->category_id)) {
+            // Handle Category — 每次同步都更新（若有傳入）
+            if (!empty($data['category']) || empty($product->category_id)) {
                 $categoryName = $data['category'] ?? '未分類';
                 $category = Category::firstOrCreate(
                     ['name' => $categoryName],
@@ -55,8 +56,8 @@ class ProductService
                 $product->category_id = $category->id;
             }
 
-            // Handle Base Unit (Default: 個)
-            if (empty($product->base_unit_id)) {
+            // Handle Base Unit — 每次同步都更新（若有傳入）
+            if (!empty($data['unit']) || empty($product->base_unit_id)) {
                 $unitName = $data['unit'] ?? '個';
                 $unit = Unit::firstOrCreate(['name' => $unitName]);
                 $product->base_unit_id = $unit->id;
@@ -69,4 +70,15 @@ class ProductService
             return $product;
         });
     }
+
+    /**
+     * 透過外部 POS ID 查找產品。
+     *
+     * @param string $externalPosId
+     * @return Product|null
+     */
+    public function findByExternalPosId(string $externalPosId)
+    {
+        return Product::where('external_pos_id', $externalPosId)->first();
+    }
 }